The present invention relates to an apparatus for molding recorded discs and particularly to such an apparatus which molds indicia statements on the disc along with the recorded information.
Recorded discs generally comprise a circular, flat plate or disc of a plastic material having a center hole therethrough and recorded information provided therein in the form of a surface relief pattern formed along a spiral path in the major surfaces of the disc. The surface relief pattern preferably may be formed in a spiral groove in the disc. The center portion of the disc is generally left blank and, for audio records, a label is adhered onto the blank center portion which contains information as to what is recorded in the disc and legal information, such as a copyright notice. Recently there has been developed recorded discs, such as video discs, which do not have a label on their center portion but which are placed in a container which has the information thereon. However, for such discs it is still desirable to provide the legal information, such as the copyright notice, directly on the disc.
The recorded discs are generally made in a mold press having a pair of opposed mold plates, at least one of which is movable toward and away from the other, and a stamper on the opposed surfaces of each mold plate. The stampers are thin metal sheets having on one surface thereof indentations or projections which are the negative of the information to be formed on the surface of the disc. Each stamper generally has a central opening therethrough through which a center hold down member extends into an opening in the mold press to secure the inner edge of the stamper to the mold plate. The area of the center hold down member provides the major portion of the blank area of the center of the disc. Because of the manner in which the stampers are made, it is difficult and expensive to provide the stampers with indentations or projections in the form which will form the desired indicia information on the center of the disc.